The tissue of cities is getting increasingly dense and compact, however, according to the current development models, the demand for living space per person, for industrial and commercial activities, for the transport infrastructure, requires more and more land, often to the detriment of agricultural fields, that surround cities. The occupation of agricultural lands has significant impact on the resilience of cities to the effects of climatic changes; in fact, permeable land and green areas play a fundamental role on the mitigation of climate (avoiding heat waves, floods) on the quality of life and on the ecosystems. The soil is a precious resource for the common wealth, hence, the EU Commission is committed to reducing land (ab) use and aim to "no net land take by 2050" initiative, that would imply that all new urbanisation will either occur on brownfields, used lands, ex-industrial buildings or that any new land used will need to be compensated by reclamation of artificial land. Starting from those premises, the topic of this paper is addressed to show how it is possible to avoid new land use, re-using the industrial legacy to produce food more efficiently, to be more productive and to guarantee food safety through innovative indoor technology, such as hydroponic systems. By exploring and analyzing the experiences of different case studies, set in European and North American cities, I aim to investigate and illustrate, through some architectural projects, how "agricultural factories" can be considered a replicable sustainable model of urban regeneration to improve urban food production and city-life quality.